CDA stands for "Compact Disc Audio." Invented in 1979, and then introduced into the United States in 1983, CDA discs have become quite popular because they can be played in all computers, all home CD players, all car stereos, all portable ("Walkman" style) players, and even in most home DVD players. However, only 80 minutes of recording time can be placed on each disc. Consequently, the CDA format requires many more discs to produce and handle. Therefore, CDA discs are also very much more expensive than MP3 discs.
In most cases, purchasing MP3 discs will save so much money that you can easily buy any player you want for home or car use with the cash you save by NOT buying the regular CDA discs.